Tabulated Tissue Conductivity Data

Furthermore, the values are dependent on frequency, temperature, water content, blood perfusion, and the status of the body. The electrical properties of tissue wiU also change under compression (Belmont et al., 2013). The difference between data from human and mammalian animal tissue is usually considered small. The biomaterial may be in vivo or ex vivo tissue, excised material from freshly killed animals, or human autopsy material obtained a day or two after death. 

Electrical tissue data have been tabulated by many authors in many review articles and book chapters Schwan and Kay (1957), Schwan (1963), Geddes and Baker (1967), 

Foster and Schwan (1986), Stuchly and Stuchly (1990), Duck (1990), and Holder (2005). Gabriel et al. (1996a) made a literature survey. Their own measurements (Gabriel et al., 1996b) were made with a two-electrode technique and a coaxial probe in the frequency range of 10 Hz to 20 GHz. In that way, the transfer impedance component was eliminated. 

Therefore, problems with tabulated values include the following  

In Section 3.8 about dispersions, the use of permittivity or conductivity parameters was discussed. From Section 2.3.4, we know that conductivity is dependent on the density of charge carriers and their mobility. In the frequency range less than 10 MHz, tissue admittance is usually dominated by the conductivity of the body electroljrtes, but at higher frequencies it is dominated by the dielectric constant. The electroljrtes without cells, in particular urine and cerebrospinal fluid (CSF), have the highest low-frequency conductivity thus, the higher the cell concentration, the lower the low-frequency conductivity. Tooth, cartilage and bone, lipids, fat, membranes such as the skin stratum comeum (SC), and connective tissue may contain many inorganic materials with low conductivity, but they are very dependent on body liquid perfusion. Tissue conductivity data are tabulated in Table 4.2. 

---